This invention relates to the field of traffic engineering, and in particular to the interactive maintenance and enhancement of routes for virtual circuits, such as Label-Switched Paths (LSPs), subject to routing and other network traffic constraints.
Traffic engineering generally includes the tasks of predicting the behavior of communications networks, and modifying the behavior as required to provide an efficient and effective use of resources throughout the network. Traffic Engineering includes the process of creating ‘virtual circuits’ between source and destination nodes in order to make efficient use of network resources, to satisfy routing constraints for the circuits, and to improve network survivability. In the field of Multi-Protocol Label Switching, for example, traffic engineering includes determining primary and secondary routes for Label Switched Paths (LSPs).
A variety of tools and techniques have been developed to identify optimal, or near-optimal, configurations of modeled networks. In the field of label switching network configurations, tools are available to align the requirements placed on defined communication paths (LSPs) between nodes of the network with the resources available in an existing or proposed network, and thereby identify near-optimal routes for these virtual circuits.
As networks become more and more complex, with dynamic changes occurring regularly, the actual optimization of a network's performance becomes a daunting and sometimes infeasible or impractical task. When a change or addition to a network is implemented, the truly-optimal use of this changed or added resource may require a change to dozens, or hundreds, of other network resources. In like manner, when a change or addition to the communication requirements or constraints is made, the truly-optimal solution may also require many changes to the network. Often, due to the risks of introducing unanticipated problems with each change, and the well recognized maxim of “if it isn't broken, don't ‘fix’ it”, few, if any, of the ancillary changes are actually implemented. Because of these factors, and others, most real-world networks gradually become substantially different from their ideally optimized configuration.
Conventional optimization tools and techniques receive a model of the network, including the capabilities of each link, and a list of required circuits between nodes and their associated constraints. The conventional tools then apply one or more allocation schemes to determine a preferred route for each circuit so as to satisfy each of the constraints subject to the network capabilities. Unfortunately, the resultant preferred or optimal solution often has little correspondence to the current configuration of the network, and the number of changes required to implement the proposed solution makes such an implementation infeasible or impractical.
Copending U.S. patent application Ser. No. 11/778,053, “CONTROLLED INCREMENTAL MULTI-PROTOCOL LABEL SWITCHING (MPLS) TRAFFIC ENGINEERING”, filed 15 Jul. 2007 for Gordon Bolt, Edward A. Sykes, and Yu Liu, incorporated by reference herein, addresses this problem by limiting the scope of the optimization process. The system assesses an existing network configuration and identifies the potential changes to the existing configuration that provide the greatest incremental improvements to the performance of the network. Typically, the user of the system identifies the maximum number (N) of changes that may be implemented in an existing network, and the system provides a set of possible reconfigurations, each requiring fewer than N changes.
In each of these processes, the user has little to no control of the selection of routes to be assessed and/or modified, other than to ‘lock’ routes that must not be changed, or otherwise constrain the optimization process in the hope of forcing it to address particular routes of interest. Conceptually, these processes are well suited for ‘strategic’ or ‘global’ traffic engineering, but are poorly suited for ‘tactical’ or ‘operational’ traffic engineering.
Often, a network manager is aware of routes that are experiencing poorer than expected performance, or routes of particular importance that warrant frequent tune-ups to assure optimal performance. If the network manager is unable or unwilling to allow the conventional traffic engineering optimization processes to find a solution that may call for the re-routing of routes that are not currently experiencing problems, improving a particular route's performance becomes an ad-hoc process. Because of the multiple dependencies among routes of a network, however, the ad-hoc improvement of one route may introduce problems and/or cause degraded performance on other routes, often with significant unforeseen consequences. In many cases, the degraded performance occurs over the course of multiple ad-hoc changes, and the identification of the particular change(s) that needs to be undone to restore the network to its past performance capabilities is, at best, challenging.
It would be advantageous to provide an interactive system that allows a network manager or traffic engineer to address one or more specified routes for customized traffic engineering optimization, based on potential changes to the specified routes. It would be advantageous to allow the user to define the constraints that are to be used by the system in identifying the potential changes to the specified routes. It would be also be advantageous to record any changes selected by the user for implementation, and to generate the data necessary to reconfigure the network to effect the selected change(s).
These advantages, and others, can be realized by an interactive system and method that automates the control and management of routing changes that are focused on specific routes or particular network hot spots. Based on the premise that the user is aware of a particular problem that needs to be solved, the system leads the user through an end-to-end process from the identification of the problem to the generation of configuration instructions for effecting a selected solution. A graphic user interface provides a visualization of the current routing and alternative routings, to facilitate the analysis and selection of an improved routing, if any. Throughout the process, the effect of each proposed routing change on the overall network performance is monitored, so that the selection of a preferred solution can be made in the appropriate context, and globally sub-optimal solutions can be avoided.
Throughout the drawings, the same reference numerals indicate similar or corresponding features or functions. The drawings are included for illustrative purposes and are not intended to limit the scope of the invention.